Continuum Force Microscopy Study of the Elastic Modulus, Hardness and Friction of Polyethylene and Polypropylene Surfaces

Gracias, David H.; Somorjai, Gábor A.

doi:10.1021/ma970683b

Cited by 102 publications

(88 citation statements)

References 34 publications

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“…28,29 As the sample is probed by the tip at a constant force, soft regions will deform more than stiff regions. Thus, soft regions will appear to be lower in height.…”

Section: Resultsmentioning

confidence: 99%

AFM of Poly(vinyl alcohol) Crystals Next to an Inorganic Surface

2001

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Crystallization of poly (vinyl alcohol) in the presence of an inorganic filler surface (sodium montmorillonite, MMT) was observed and compared to the crystallization of the neat polymer. For this purpose, several atomic force microscopy modes, providing spatial resolution between amorphous and crystalline polymer, are employed to observe filled and unfilled PVA films. The various AFM modes utilized are detailed, with the emphasis on how they can contrast stiff (crystalline) and softer (amorphous) domains on a polymer surface. The study revealed changes in the PVA crystal morphology, with bulk crystallites growing to sizes of more than 5 µm, whereas next to the inorganic surfaces grow to only 1-2 µm in size. Moreover, complementary X-ray diffraction and DSC investigations indicate a new crystal structure formed next to the MMT surfaces, at the expense of the bulklike crystal.

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“…28,29 As the sample is probed by the tip at a constant force, soft regions will deform more than stiff regions. Thus, soft regions will appear to be lower in height.…”

Section: Resultsmentioning

confidence: 99%

AFM of Poly(vinyl alcohol) Crystals Next to an Inorganic Surface

2001

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“…The values of Elastic modulus and Poisson's ratio were assumed to be similar to that of LDPE, using = 0.47 and = 0.5 [5]. The thickness of the samples (the length of the interface) was 4.0 (see Fig.…”

Section: A Test Samplesmentioning

confidence: 99%

Breakdown strength of solid|solid interface

Hasheminezhad

Ildstad

Nysveen

2010

2010 10th IEEE International Conference on Solid Dielectrics

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Abstract-Interfaces between solids are generally considered weak regions in electrical insulation systems. This is particularly so if the electrical stress is applied parallel to the interface. Important parameters, affecting the breakdown strength, are interface pressure, humidity, presence of liquid dielectric and the surface roughness of the solid in contact. The main aim of the work presented here is to examine, theoretically and experimentally, the effect of interfacial pressure and roughness on the tangential breakdown strength. The size and gas pressure of enclosed surface voids were estimated using mechanical contact theory. The dielectric 50 AC tangential strength of XLPE|XLPE interface was investigated for various values of pressure and roughness. The increase in breakdown strength due to increased pressure was largest in case of surfaces with the high degree of roughness. As expected the highest breakdown strength was observed in case of the smoothest surfaces. The estimated results of void size and gas pressure were found to be in good agreement with the experimental observations.

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“…30 mJ m K2 for polypropylene on glass; Gracias & Somorjai 1998). By linearizing equation (4.3) about F n Z0, we can express the necessary tangential force for sliding as a function of the normal load F n :…”

Section: Frictional Adhesion Cantilever Modelmentioning

confidence: 99%

Sliding-induced adhesion of stiff polymer microfibre arrays. II. Microscale behaviour

Schubert

Lee

Majidi

et al. 2008

J. R. Soc. Interface.

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The adhesive pads of geckos provide control of normal adhesive force by controlling the applied shear force. This frictional adhesion effect is one of the key principles used for rapid detachment in animals running up vertical surfaces. We developed polypropylene microfibre arrays composed of vertical, 0.3 mm radius fibres with elastic modulus of 1 GPa which show this effect for the first time using a stiff polymer. In the absence of shear forces, these fibres show minimal normal adhesion. However, sliding parallel to the substrate with a spherical probe produces a frictional adhesion effect which is not seen in the flat control. A cantilever model for the fibres and the spherical probe indicates a strong dependence on the initial fibre angle. A novel feature of the microfibre arrays is that adhesion improves with use. Repeated shearing of fibres temporarily increases maximum shear and pull-off forces.

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Continuum Force Microscopy Study of the Elastic Modulus, Hardness and Friction of Polyethylene and Polypropylene Surfaces

Cited by 102 publications

References 34 publications

AFM of Poly(vinyl alcohol) Crystals Next to an Inorganic Surface

AFM of Poly(vinyl alcohol) Crystals Next to an Inorganic Surface

Breakdown strength of solid|solid interface

Sliding-induced adhesion of stiff polymer microfibre arrays. II. Microscale behaviour

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